Neptune's big moon Triton was nameless for over a hundred years after its discovery. And it was so far away that astronomers knew almost nothing about it. Then Voyager 2 visited and saw active ice volcanoes on a moon that is probably a cousin to Pluto.

In northern hemisphere summer, the ancient zodiac constellation Sagittarius stands low on the southern horizon. It's a special constellation, for when you see Sagittarius, you're looking into the heart of the Milky Way.

In the ABC of astronomy, astronomy itself is the first and most important item. What is astronomy and how does it differ from astrology? What are the main specialist areas in astronomy and how do they contribute to the overall picture?

We no longer see the heavens as perfect and the stars as eternal and unchanging. Even the Universe had a beginning, and everything that we observe changes and evolves. Many of these changes involve cosmic collisions.

If stars aren't white, why isn't the night sky more colorful? If it's 93 million miles to the Sun, how many times farther away is the next nearest star? Will the Sun become a black hole and suck us in? Here's a short explanation of some common misconceptions about the stars.